1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device with a liquid crystal panel which can be displayed in any other color instead of a black color during a non-driving mode through the use of one-color film for selectively reflecting light with a predetermined wavelength. Although the present invention is suitable for a wide scope of applications, it is particularly suitable for displaying the liquid crystal panel with the same color as that of an external case during the non-driving mode of the liquid crystal panel.
2. Discussion of the Related Art
Generally, an active matrix type LCD device displays images by controlling light transmittance of liquid crystal through a thin film transistor (hereinafter, referred to as “TFT”) serving as a switching element. The LCD device has been widely used in various fields of portable information devices, office devices, computer and IT products, and etc., owing to the advantageous properties of low power consumption, thin profile, and lightness in weight.
The LCD device cannot emit light in itself. Thus, it is necessary to additionally provide light to the LCD device. The LCD device can display images through the use of light emitted from a backlight unit positioned under a liquid crystal panel or ambient light provided from the external. When maximizing transmittance of light through a liquid crystal layer of the liquid crystal panel, a white-colored image with high luminance can be displayed on the liquid crystal panel. Meanwhile, when minimizing transmittance of light through the liquid crystal layer of the liquid crystal panel, a black-colored image with low luminance can be displayed on the liquid crystal panel.
Hereinafter, an LCD device according to the related art will be described in detail with reference to the accompanying drawings.
FIG. 1 is a perspective view illustrating the LCD device according to the related art.
Referring to FIG. 1, the LCD device according to the related art includes a liquid crystal panel provided with a lower substrate 10, an upper substrate 20, and a liquid crystal layer (not shown) formed between the lower and upper substrates 10 and 20; a backlight unit (not shown) for supplying light to the liquid crystal panel; and a driving circuit (not shown) for driving the liquid crystal panel.
On the lower substrate 10 of the liquid crystal panel, there are gate and data lines 11 and 12, and a thin film transistor 13. The gate and data lines 11 and 12 cross at right angles to each other, that is, are perpendicular to each other, to thereby define a pixel region. The thin film transistor 13 is formed at a crossing of the gate and data lines 11 and 12, wherein the thin film transistor 13 functions as a switching element.
In the pixel region, there is a pixel electrode 14 of a transparent conductive material such as ITO (Indium Tin Oxide), wherein the pixel electrode 14 is formed in parallel to the data line 12, and is electrically connected with the thin film transistor 13.
On the upper substrate 20 of the liquid crystal panel, there are a light-shielding layer 21 and a color filter layer 22. The light-shielding layer 21 prevents the light from leaking in the gate line 11, the data line 12, and the thin film transistor 13. The color filter layer 22 is interposed between each light-shielding layer 21, wherein the color filter layer 22 selectively transmits only light with a predetermined wavelength. In this case, the color filter layer 22 comprises red (R), green (G), and blue (B) color filters.
Also, a lower polarizing film 31 is formed on a rear surface of the lower substrate 10, and an upper polarizing film 32 is formed on the upper substrate 20. A passivation substrate 40 is formed on the upper polarizing film 32 so as to protect the lower and upper substrates 10 and 20.
When the thin film transistor 13 is turned-on by a diving signal applied to the gate line 11, an analog data signal applied to the data line 12 is applied to the pixel electrode 14 through a channel layer of the thin film transistor 13. Through the aforementioned process, it is possible to control the light transmittance of liquid crystal. Then, the light transmitted through the liquid crystal layer passes through the color filter layer 22, thereby displaying full-color images.
FIG. 2 is a plane view illustrating a mobile LCD terminal 70 (hereinafter, referred to as “terminal”) with the LCD device according to the related art.
As shown in FIG. 2, the terminal 70 includes the aforementioned liquid crystal panel 50; a backlight unit (not shown) for supplying the light to the liquid crystal panel 50; a driving circuit (not shown) for driving the liquid crystal panel 50; and an external case 60 for covering the liquid crystal panel 50.
As mentioned above, when the terminal 70 according to the related art is in a non-driving mode, that is, power is not applied to the terminal 70, the light emitted from the backlight unit is not supplied to the liquid crystal panel 50. Instead, the ambient light provided from the external is absorbed by the lower and upper polarizing films 31 and 32, whereby the liquid crystal panel 50 is displayed as a black-colored screen.
Recently, the terminal 70 is regarded as an accessory beyond simple communication means. That is, color and design of the external case 60 in the terminal 70 may be selected among the most important factors in determining the consumer's preference for the product. In this respect, there is a growing tendency for the external case 60 to use the various colors as well as black or white.
However, the terminal 70 according to the related art is formed in such a way that the liquid crystal panel is displayed only with the black color during the non-driving mode. During the non-driving mode, the external case 60 is different from the liquid crystal panel in color, which might cause a decline in consumer's preference.